NtrC-sensed nitrogen availability is important for oxidative stress defense in Pseudomonas putida KT2440

Abstract

The zwf, which encodes glucose-6-phosphate dehydrogenase, is repressed by NtrC under nitrogen-limited condition. Previously, we demonstrated that induction of zwf-1 is required for protecting Pseudomonas putida cells under oxidative stress, which could be possible probably because of derepression of HexR on the zwf-1 gene under oxidative stress. These findings led us investigate that NtrC still represses the zwf-1 under nitrogen-limited oxidative stress condition, which makes cells more sensitive under such condition. Interestingly, deletion of the ntrC gene significantly reduces growth rate, but renders cells more resistant to oxidative stress, under nitrogen limited condition in P. putida. More vitality of the ntrC mutant under oxidative stress condition was also confirmed by the fluorogenic redox dye using flow cytometry. The results of transcriptome analysis demonstrated that the derepression of several oxidative stress genes along with the zwf-1 gene might confer high resistance to oxidative stress in the ntrC mutant. Here, we presented the data for the first time, showing that different sets of genes are involved in nitrogen-rich and nitrogen-limited oxidative stress conditions and NtrC-sensed nitrogen availability is one of the most important prerequisite for full cellular defense against oxidative stress in P. putida.